| Do you think it should be that general? I was thinking the discount | should only apply in the situtation where a case expression contains an | expression with one free varaible that is a function argument, and all | operations are primitive. Well, if you see x >=# 0 then it'd be good to inline if argument x was bound to a literal, even if the >= is not scrutinised by a case. Why? Because then we can constant-fold it away. But perhaps the discount should be smaller? | So, is there a way of deciding if a primitive op will be rewritten if all | its arguements are given? The constant-folding rules for the primops are all in prelude/PrelRules.lhs in function primOpRules. Please add more rules. For example, I see that x +# 0 = x is not in there! Simon